Cutaneous innervation of the arm.

1. Cutaneous innervation of the arm. • Lateral side of arm :1-supraclavicular :supply skin over shoulder & upper ½ of deltoid. 2-upper lateral cutaneous N. of arm: a branch of axillary, supplies skin over lower ½ of deltoid. 3-lower lateral cutaneous N. of arm : a branch of radial, supplies skin over lateral side of arm below deltoid. • Medial side of arm :1-inter-costo-brachial N. : supplies skin of upper part of medial side of arm (close to axilla). 2-medial cutaneous N. of arm :a branch of medial cord, supplies medial side of arm below axilla.

2. Superficial & deep veins of the arm. Deep veins1-venae comitantes, which accompany large arteries. 2-axillary vein. superficial veins1-cephalic vein :ascends insuperficial fasciaon lateral side of biceps, then it piercec clavi-pectoral fascia to end in axillary V.2-Basilic vein :ascends insuperficial fascia on medial side of biceps, halfway up the arm, it pierces deep fascia to join venae cometantes of brachial artery and its continuation forms axillary vein at the lower border of teres major. Note the common variations seen in the region of elbow.

3. Superficial & Deep lymphatics of the arm • Superficial L.Vs. :1-from lateral side of arm accompany the cephalicvein and end in infraclavicular lymph nodes.2-from medial side of arm accompany the basilicvein, and end in lateral group of axillary L.Ns. • Deep L.Vs. : end in lateral group ofaxillary L.Ns.

5. The Arm • Fascial compartment of upper arm : • The upper arm is enclosed in a sheath of deep fascia. • 2 fascial septa on the medial & lateral sides extend from thissheath into medial &lateral supracondylar ridges of humerus respectively. • so., the arm is divided into an anterior & posterior fascial compartment containing Ms., nerves & vessles. Cross section of arm .Note division of arm by the humerus , medial & lateral intermuscular septa into anterior & posterior compartements.

6. Front of the arm • Biceps brachii. • Coracobrachialis. • Brachialis. • Brachial artery. • Musculocutaneous nerve. • Median nerve. • Upper part of ulnar nerve.

7. Front of the Arm Supraglenoid tubercle of scapula Into middle of medial border of humerus. Into deep fascia on medial side of forearm. By strong Tendon into Biceps & Coracobrachialis • Nerve Supply : Musculocutaneous N. • Action :Biceps : flexion of elbow + powerful supinator of radioulnar joint.s. Coracobrachialis + short head of biceps : help in flexion of shoulder joint.

8. Front of lower ½ of shaft of humerus Middle of medial border of humerus Coracobrachialis Brachialis Nerve Supply :Musculocutaneous N. Its lateral fibres are supplied by Radial N. Action : Flexion of Elbow j.

9. Back of the Arm Triceps Muscle Origin :by 3 heads :Long Head : from infraglenoid tubercle of scapula. Lateral Head : from olique ridge on posterior surface of humerus above spiral groove. It covers the Radial nerve. Medial Head : from posterior surface of humerus below spiral groove.Insertion : Olecranon process of ulna (upper surface). Nerve Supply : Radial N. Action : extension of elbow j. - long head supports head of humerus in abducted shoulder.

10. Muscles of Arm Powerful powerful Middle of Its lateral part is supplied by radial N. Oliquee ridge on Above spiral groove Below spiral groove

11. Structures passing through anterior fascial compartment :1- Brachial artery : It begins at lower border ofteres major as a continuation of axillary artery. • It terminates opposite neck of radius by dividing into radial & ulnar arteries. • Anteriorly :At its upper part : it is overlapped lateraly–By medial margin of biceps & coracobrachialis. At its middle part :It is crossed by Median N. At its lower part (at the cubital fossa) : It is crossed by Biciptal aponeurosis.

12. Posteriorly :triceps + radial N. insertion of coracobrachialis +brachialis. • Medially :ulnar N.(at its upper part) + median N.(at its lower part). • Laterally :above…median N., biceps & coracobrachialis. below… biceps tendon.

13. Branches of brachial artery : 1-muscular------ 2-nutrient to humerus. 3-profunda brachii A.----arise near origin of brachial artery , following radial N. into spiral groove of humerus. 4-superior ulnar collateral A.— it follows ulnar N. and shares inanastomosis around elbow joint. 5-inferior ulnar collateral A.-arises near termination of the artery and shares in anastomosis around elbow

15. Anastomosis around elbow • In front of lateral epicondyle : between anterior descending branch ofprofunda artery & radial recurrent artery. • Behind lateral epicondyle : between posterior descending branch ofprofunda artery & interosseous recurrent artery. • In front of medial epicondyle : between anterior branch of inferior ulnar collateral artery & anterior ulnar recurrent artery. • Behind medial epicondyle : between superior ulnar collateral + posterior branch of inferior ulnar collateral artery & posterior ulnar recurrent artery. branch of posterior interosseous artery (branch of ulnar artery)

16. 2-Musculocutaneous Nerve • Origin : lateral cord of brachial plexus in axilla. • Course : It descends downward and laterally,piercing coracobrachialis muscle, and then passes betweenbiceps & brachialis. It appears at lateral margin of biceps tendon, piercing deep fascia above elbow, where it descends as lateral cut. N. of forearm on the lateral aspect of forearm. • Branches : 1-muscular (biceps, coracobrachialis, +brachialis). .2-Cutaneous: lateral cutaneousnerve offorearm to supply skin of front & lateral sides of forearm down to the root of thumb. 3-articular : to elbow joint.

17. 3-Median Nerve • origin :medial & lateral Cords of brachial plexus in axilla. • Course :above,it descends on lateral side of brachial artery. -At the middle of arm, it crosses the brachial artery. Then it descends on the medial side of the artery. - At the elbow ,it is crossed by the biciptal aponeurosis. • Has No branches in the upper arm.

18. Structures passing through post.compartment :1-Ulnar Nerve • Origin :medial cord of brachial plexus in axilla. • Course :above, it is covered posteriorly by medial head of triceps. -it descends medial to the brachialartery as far as the middle of the arm, where the insertion ofcoracobrachialis, it pierces medial facial septum , accompanied by superior ulnar collateral artery to descend in the post. compartment of arm, passing behind medial epicondyleto enter forearm bet.2 heads of flexor carpi ulnaris. • It has No branches in the arm. • Only, it has articular to elbow joint. 2- Profunda brachii artery

19. 3-Radial Nerve • Origin :post.cord of brachial plexus in the axilla. • Course : -on leaving axilla, it passes immediately into post. compartment of arm where it descends in spiralgroove of humerus , accompanied by profunda brachii artery, deep to lateral head of triceps. -Then,it pierces lateral facial septum above elbow to enter anterior compartment of arm,between brachialis (medially) and brachioradialis & extensor carpi radialis longus (laterally). -At the front of lateral epicondyle, it terminates into superficial & deep branches. N.B:deep branch is called post. Interosseous N.,passes through supinator muscle to reach back of forearm./ and superficial branch is the continuation of radial N.,descends as small N.in front of forearm to reach dorsum of hand (to supply lateral part of dorsum of hand+ proximal parts of lateral 31/2 fingers ).

20. Branches of the Radial nerve • In the axilla : 1-post.cut.N.of arm. 2-branches to long head of triceps. • In the Spiral groove : 1-branches to lateral & medial headsof triceps. 2-branch to anconeus. 3-lateral cut. N. of arm. 4-post. Cut.n.of forearm. • In anterior compartment of arm above elbow, ( in deep groove bet. brachialis & brachioradialis): 1-Muscular : brachialis (lateral ½),brachioradialis, & extensor carpi radialis longus. 2-Articular : elbow joint.

21. In front of lateral epicondyle of humerus, it divides into two terminal branches : 1-superficial branch.2-deep branch (posterior interosseous N.).